Alcohol (e.g., ethanol and/or butanol) and other fermentation products may be produced from grain-based feedstocks (e.g. corn, sorghum/milo, barley, wheat, soybeans, etc.), from sugar (e.g. from sugar cane, sugar beets, etc.), and from biomass (e.g. from cellulosic feedstocks such as switchgrass, corn cobs and stover, wood or other plant material).
In a biorefinery configured to produce ethanol from biomass such as cellulosic feedstocks as indicated above, ethanol can be produced from lignocellulosic material (e.g. cellulose and/or hemi-cellulose). The biomass is typically prepared so that sugars in the cellulosic material (such as glucose from the cellulose and xylose from the hemi-cellulose) can be accessed and fermented into a fermentation product that includes ethanol (among other things). The fermentation product can then be transferred to a distillation system, where the ethanol can be recovered by distillation and dehydration. Other bioproducts such as lignin and organic acids may also be recovered as co-products.
In addition to generating ethanol (or other desired fermentation product) a number of ancillary chemicals may also be produced during one or more of biomass pretreatment, saccharification, fermentation, or even distillation. Such chemicals include substances such as acetic acid, furfural (furan-2-carbaldehyde), and diacetyl (2,3-butanedione). Some of these compounds may be recovered or recycled, but other compounds require management or remediation in order for the cellulosic biorefinery to operate effectively. In particular, the presence of diacetyl may be particularly problematic as it concentrates along with ethanol during distillation and molecular sieving. Not only can diacetyl cause green coloring of the ethanol to an undue degree (thereby limiting the ethanol's downstream uses), diacetyl can also cause the ethanol to become more acidic over time. For fuel ethanol these are typically undesirable traits and can make remediation of the diacetyl desirable.
One common technique for managing undue amounts of diacetyl in cellulosic ethanol includes aging the ethanol so that the diacetyl breaks down naturally. Another common technique includes blending the ethanol/diacetyl mixture with a much larger volume of starch derived ethanol so as to dilute the diacetyl, thereby decreasing the concentration of diacetyl.
Unfortunately, as cellulosic ethanol becomes more prevalent, the volumes can reach levels such that storage for long periods to “age” the diacetyl can be uneconomical, and blending may become difficult due to the vast amounts of starch based ethanol required.
It would be advantageous to provide for systems and methods for cellulosic fermentation product treatment that can rapidly and economically remediate diacetyl. It would further be advantageous to provide for systems and methods for such treatment that integrates into the functionality of a commercial scale ethanol production facility.